U.S. patent application number 13/057827 was filed with the patent office on 2011-06-02 for method for inferring temperature in an enclosed volume.
This patent application is currently assigned to ROLLS-ROYCE FUEL CELL SYSTEMS LIMITED. Invention is credited to Gerard D. Agnew.
Application Number | 20110129934 13/057827 |
Document ID | / |
Family ID | 39812164 |
Filed Date | 2011-06-02 |
United States Patent
Application |
20110129934 |
Kind Code |
A1 |
Agnew; Gerard D. |
June 2, 2011 |
METHOD FOR INFERRING TEMPERATURE IN AN ENCLOSED VOLUME
Abstract
A method for inferring temperature in an enclosed volume
containing a fuel/oxidant mixture, the method comprises placing at
least one wire in the enclosed volume. The at least one wire having
an identifiable property wherein the identifiable property of the
at least one wire changes from a first identifiable state at a
temperature below the auto-ignition temperature of the fuel/oxidant
mixture to a second identifiable state at a temperature above the
auto-ignition temperature of the fuel/oxidant mixture, and
determining if the identifiable property of the at least one wire
has changed from the first identifiable state to the second
identifiable state and hence if the temperature in the enclosed
volume is above the auto-ignition temperature of the fuel/oxidant
mixture.
Inventors: |
Agnew; Gerard D.; (Derby,
GB) |
Assignee: |
ROLLS-ROYCE FUEL CELL SYSTEMS
LIMITED
DERBY
GB
|
Family ID: |
39812164 |
Appl. No.: |
13/057827 |
Filed: |
July 10, 2009 |
PCT Filed: |
July 10, 2009 |
PCT NO: |
PCT/EP2009/005010 |
371 Date: |
February 7, 2011 |
Current U.S.
Class: |
436/84 ; 324/691;
436/73 |
Current CPC
Class: |
Y02E 60/50 20130101;
G01N 31/22 20130101; G01K 7/183 20130101; G01K 3/005 20130101; G01N
33/84 20130101; H01M 8/0432 20130101; H01M 8/0444 20130101; H01M
2008/1293 20130101; H01M 8/04656 20130101 |
Class at
Publication: |
436/84 ; 436/73;
324/691 |
International
Class: |
G01N 33/20 20060101
G01N033/20; G01R 27/08 20060101 G01R027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2008 |
GB |
0815017.9 |
Claims
1-17. (canceled)
18. A method for inferring temperature in an enclosed volume, the
enclosed volume containing a fuel/oxidant mixture or being supplied
with a fuel and an oxidant to form a fuel/oxidant mixture in the
enclosed volume, the method comprising: (i) placing at least one
wire in the enclosed volume), the at least one wire having an
identifiable property wherein the identifiable property of the at
least one wire changes from a first identifiable state at a
temperature below the auto-ignition temperature of the fuel/oxidant
mixture to a second identifiable state at a temperature above the
auto-ignition temperature of the fuel/oxidant mixture; and (ii)
determining if the identifiable property of the at least one wire
has changed from the first identifiable state to the second
identifiable state and hence if the temperature in the enclosed
volume is above the auto-ignition temperature of the fuel/oxidant
mixture.
19. A method according to claim 18 wherein the method further
comprises indicating that the identifiable property of the at least
one wire has changed from the first identifiable state to the
second identifiable state and hence the temperature in the enclosed
volume is above the auto-ignition temperature of the fuel/oxidant
mixture.
20. A method according to claim 18 wherein the enclosed volume is a
volume encased by the at least one wire.
21. A method according to claim 18 wherein the enclosed volume is a
volume between an outer volume and an inner volume, the outer
volume encasing the inner volume.
22. A method according to claim 18 wherein the identifiable
property of the at least one wire is electrical resistance.
23. A method according to claim 22 wherein the first identifiable
state is electrical resistance and the second identifiable state is
electrical conductance.
24. A method according to claim 18 wherein the identifiable
property of the at least one wire is electrochemical state.
25. A method according to claim 24 wherein the first identifiable
state is an oxidised state and the second identifiable state is a
reduced state.
26. A method according to claim 18 wherein the at least one wire is
selected from the group consisting of Pt, Pd, Rh, Ru and alloys
thereof.
27. A method according to claim 26 wherein the at least one wire is
substantially Pd.
28. A method according to claim 18 wherein a plurality of spokes
are arranged on the at least one wire.
29. A method according to claim 28 wherein the plurality of spokes
are thermally conducting.
30. A method according to claim 29 wherein the plurality of spokes
are selected from the group consisting of Cu, Ni, W, Ag, alloys
thereof and diamond coating.
31. A method according to claim 18 wherein the enclosed volume is
disposed within a fuel cell.
32. A method according to claim 31 wherein the enclosed volume is
disposed within a solid oxide fuel cell.
33. A method according to claim 18 wherein the enclosed volume is
disposed within a reformer.
34. A method according to claim 33 wherein the enclosed volume is
disposed within a hydrocarbon reformer.
35. A method for inferring temperature in an enclosed volume, the
enclosed volume containing a fuel/oxidant mixture or being supplied
with a fuel and an oxidant to form a fuel/oxidant mixture in the
enclosed volume, the method comprising: (i) placing at least one
wire in the enclosed volume), the at least one wire having an
identifiable property wherein the identifiable property of the at
least one wire changes from a first identifiable state at a
temperature below the auto-ignition temperature of the fuel/oxidant
mixture to a second identifiable state at a temperature above the
auto-ignition temperature of the fuel/oxidant mixture; and (ii)
determining if the identifiable property of the at least one wire
has changed from the first identifiable state to the second
identifiable state and hence if the temperature in the enclosed
volume is above the auto-ignition temperature of the fuel/oxidant
mixture, the identifiable property of the at least one wire is
electrochemical state and wherein the first identifiable state is
an oxidised state and the second identifiable state is a reduced
state.
Description
[0001] The present invention relates to a method for inferring
temperature in an enclosed volume and in particular to a method for
inferring temperature in an enclosed volume disposed within a fuel
cell.
[0002] It is known that a fuel cell arrangement comprises one or
more fuel cell modules, each fuel cell module comprises a plurality
of fuel cells arranged within a housing and the housing of each
fuel cell module is arranged within a pressure vessel.
Conventionally the pressure vessel has internal insulation and/or
cooling fluid using passages within the pressure vessel to maintain
the temperature of the pressure vessel at a sufficiently low
temperature to guarantee the integrity of the pressure vessel. In
the case of solid oxide fuel cells operating at higher
temperatures, for example 700.degree. C. to 1,000.degree. C., the
thermal management of the heat flux to the pressure vessel is
difficult. Thermocouple devices are typically employed to monitor
such elevated temperatures. However, thermocouple devices are known
to have low signal output and to be significantly non-linear in
their response. The signal is also vulnerable to electrical noise
in practical applications, leading to unreliability issues due to
junction degradation. Furthermore, high temperature thermocouple
devices are costly.
[0003] Accordingly the present invention seeks to provide a novel
method for inferring temperature in an enclosed volume, which
reduces, preferably overcomes, the above mentioned problem.
[0004] Accordingly the present invention provides a method for
inferring temperature in an enclosed volume, the enclosed volume
containing a fuel/oxidant mixture or being supplied with a fuel and
an oxidant to form a fuel/oxidant mixture in the enclosed volume,
the method comprising placing at least one wire in the enclosed
volume, the at least one wire having an identifiable property
wherein the identifiable property of the at least one wire changes
from a first identifiable state at a temperature below the
auto-ignition temperature of the fuel/oxidant mixture to a second
identifiable state at a temperature above the auto-ignition
temperature of the fuel/oxidant mixture, and determining if the
identifiable property of the at least one wire has changed from the
first identifiable state to the second identifiable state and hence
if the temperature in the enclosed volume is above the
auto-ignition temperature of the fuel/oxidant mixture.
[0005] Preferably the method further comprises indicating that the
identifiable property of the at least one wire has changed from the
first identifiable state to the second identifiable state and hence
the temperature in the enclosed volume is above the auto-ignition
temperature of the fuel/oxidant mixture.
[0006] The enclosed volume may be a volume encased by the at least
one wire.
[0007] The enclosed volume may be a volume between an outer volume
and an inner volume, the outer volume encasing the inner
volume.
[0008] Preferably the identifiable property of the at least one
wire is electrical resistance.
[0009] Preferably the first identifiable state is electrical
resistance and the second identifiable state is electrical
conductance.
[0010] Alternatively the identifiable property of the at least one
wire is electrochemical state.
[0011] Alternatively the first identifiable state is an oxidised
state and the second identifiable state is a reduced state.
[0012] Preferably the at least one wire is selected from the group
consisting of Pt, Pd, Rh, Ru and alloys thereof.
[0013] More preferably the at least one wire is substantially
Pd.
[0014] Preferably a plurality of spokes are arranged on the at
least one wire.
[0015] More preferably the plurality of spokes are thermally
conducting.
[0016] More preferably the plurality of spokes are selected from
the group consisting of Cu, Ni, W, Ag, alloys thereof and diamond
coating.
[0017] The enclosed volume may be disposed within a fuel cell.
[0018] The enclosed volume may be disposed within a solid oxide
fuel cell.
[0019] The enclosed volume may be disposed within a reformer.
[0020] The enclosed volume may be disposed within a hydrocarbon
reformer.
[0021] The present invention will be more fully described by way of
example with reference to the accompanying drawings in which:--
[0022] FIG. 1 shows a perspective view of a first embodiment
according to the present invention.
[0023] FIG. 2 shows a perspective view of a second embodiment
according to the present invention.
[0024] FIG. 3 shows a perspective view of a third embodiment
according to the present invention.
[0025] FIG. 4 illustrates the use of the present invention in a
fuel cell arrangement.
[0026] A method for inferring temperature in an enclosed volume 10
according to a first embodiment of the present invention is shown
in FIG. 1. At least one wire 12 is placed in the enclosed volume 10
by forming the at least one wire into a shape encasing the enclosed
volume 10 whose temperature is to be inferred. In particular, the
at least one wire 12 is arranged to extend around the periphery of
the enclosed volume 10 while remaining in the enclosed volume 10.
The at least one wire 12, for example, extends circumferentially
and axially in a cylindrical casing to form a sinusoidally shaped
wire. Thus, the at least one wire 12 is positioned within a thin
region on the inside of the surface of the casing defining the
enclosed volume 10. The enclosed volume 10 initially contains a
fuel/oxidant mixture having an auto-ignition temperature. The at
least one wire 12 has an identifiable property whereby the
identifiable property changes from a first identifiable state at a
temperature below the auto-ignition temperature of the fuel/oxidant
mixture to a second identifiable state at a temperature above the
auto-ignition temperature of the fuel/oxidant mixture. The
identifiable property of the at least one wire 12 is then
determined by a determining device 14 connected to the at least one
wire 12 to see if the identifiable property has changed from the
first identifiable state to the second identifiable state and hence
if the temperature in the enclosed volume is above the
auto-ignition temperature of the fuel/oxidant mixture. A control
device 16 is provided to indicate that the identifiable property of
the at least one wire 12 has changed from the first identifiable
state to the second identifiable state and hence the temperature in
the enclosed volume is above the auto-ignition temperature of the
fuel/oxidant mixture. The control device 16 operates an alarm
system, for example an audible alarm 18 and/or visual alarm 20. The
control device 16 may also operate a pump 22 whereby the
fuel/oxidant mixture is pumped out of the enclosed volume to
prevent explosion and/or water or other extinguishing fluids are
flushed into the enclosed volume to put out the fire.
[0027] Alternatively, a fuel and an oxidant may be supplied to the
enclosed volume 10 to form a fuel/oxidant mixture in the enclosed
volume 10.
[0028] The at least one wire 12 may be a thin continuous wire or
made up of a series of wires connected continuously and wired
electrically in series.
[0029] In one embodiment, the identifiable property of the at least
one wire is electrical resistance, the first identifiable state of
the at least one wire is electrical resistance and the second
identifiable state is electrical conductance. Accordingly, the
electrical resistance of the at least one wire 12, for example a
platinum (Pt) wire, changes from being electrically resistant at
temperatures below the auto-ignition temperature of the
fuel/oxidant mixture to being electrically conducting at
temperatures above the auto-ignition temperature of the
fuel/oxidant mixture. The change in the electrical resistance may
be monitored and determined by the determining device 14, for
example, resistance measurement devices known in the art.
[0030] In another embodiment, the identifiable property of the at
least one wire 12 is electrochemical state, the first identifiable
state of the at least one wire 12 is an oxidised state and the
second identifiable state is a reduced state. Accordingly, the
electrochemical state of the at least one wire 12, for example a
palladium (Pd) wire, changes from an oxidised state at temperatures
below the auto-ignition temperature of the fuel/oxidant mixture to
a reduced state at temperatures above the auto-ignition temperature
of the fuel/oxidant mixture. The change in the electrochemical
state may be monitored and determined by the determining device 14,
for example, a change in colour of the at least one wire 12.
[0031] The at least one wire 12 is selected from the group
consisting of platinum (Pt), palladium (Pd), rhodium (Rh),
ruthenium (Ru), and alloys thereof. A threshold temperature of a
given fuel/oxidant mixture is herein defined to be a predetermined
temperature above the auto-ignition temperature of the fuel/oxidant
mixture in the enclosed volume 10. A transition temperature of the
at least one wire 12 is herein defined as the temperature close to
or at which the identifiable property changes from the first
identifiable state to the second identifiable state. For a solid
oxide fuel cell system supplied with a natural gas and an air
mixture, the threshold temperature of the solid oxide fuel cell
system needs to be maintained above approximately 800.degree. C. In
this case, the at least one wire 12 is preferably substantially Pd.
Although the transition temperature of the at least one wire 12
varies a little with the oxygen partial pressure in the solid oxide
fuel cell system, alloying of the Pd wire with a small quantity of
gold (Au) or Pt could be used to achieve the appropriate threshold
temperature. Knowledge of the auto-ignition temperature of the
fuel/oxidant mixture and the transition temperature of the at least
one wire 12 ensures the right composition of the at least one wire
12 is used, in other words the at least one wire 12 is
composition-tunable. Further, by enclosing the volume 10 in the at
least one wire 12, any localised lowering of any portion of the at
least one wire 12 below the threshold temperature results in a
sharp change in the identifiable state of the at least one wire 12
even if the remaining portion of the at least one wire 12 is above
the threshold temperature.
[0032] FIG. 2 shows another embodiment of the present invention and
like parts are denoted by like numerals. The embodiment illustrated
in FIG. 2 differs from that of FIG. 1 in that an outer volume 24
encases an inner volume 26. The outer volume 24 is provided with at
least one first wire 28. The inner volume 26 is provided with at
least one second wire 30 in a similar fashion. In this case, the
temperature of the enclosed volume 10 to be inferred is the
temperature of the volume between the outer volume 24 and the inner
volume 26. The at least one first wire 28 and the at least one
second wire 30 may be formed by one continuous wire or separate
wires electrically connected in series. The inner volume 26 may be
regions containing sources of heat sinks or cooling, such as
endothermic reforming components.
[0033] A further embodiment of the present invention is shown in
FIG. 3 and like parts are denoted by like numerals. The embodiment
illustrated in FIG. 3 differs from that of FIG. 1 in that a
plurality of spokes 32 are arranged on the at least one wire 12 in
a mesh arrangement. The plurality of spokes 32 may be thermally
conducting. The plurality of spokes 32 are selected from the group
consisting of copper (Cu), nickel (Ni), tungsten (W), silver (Ag),
alloys thereof and diamond coating, a wire having a diamond
coating. By having the plurality of spokes 32 on the at least one
wire 12, the area coverage for thermal monitoring and detection of
localised lowering of temperature below the threshold temperature
is increased. Another advantage of providing a plurality of
thermally conducting spokes 32 is that the amount of precious
metals or alloys used for the at least one wire 12 is reduced
compared to using the at least one wire 12 alone. By thinning the
at least one wire 12 and flattening its cross-sectional geometry,
the proportion of the cross-section close to the surface of the at
least one wire 12 may be increased and the rate of response could
be improved, thereby further reducing the material used for the at
least one wire 12. Further improvement in sensitivity and rate of
response could be achieved, for example, by monitoring the
conductivity of the at least one wire 12 with high frequency AC
signals that are more confined to the surface layer of the at least
one wire 12.
[0034] Turning again to FIG. 3, the at least one wire 12 may be
replaced by a layer of sintered porous conductor 34 deposited on an
electrically insulating substrate by conventional thick film or
thin film methods in order to further increase sensitivity. The top
of the enclosed volume 10 is covered with the plurality of spokes
32 and discrete thick film components 36 whereby the thick film
components 36 are electrically connected in series. By using a
plurality of discrete thick film components 36 in conjunction with
a plurality of spokes 32, a large surface coverage and hence
increased sensitivity could be achieved.
[0035] The present invention may be used within a fuel cell
arrangement described in PCT Publication No. WO 2006/106288A2, the
entire content of which is incorporated herein for reference. In
FIG. 4, the fuel cell arrangement 38 comprises at least one solid
oxide fuel cell module 40, preferably there are a plurality of
solid oxide fuel cell modules 40. Each solid oxide fuel cell module
40 comprises a hollow porous support member 42 and a plurality of
solid oxide fuel cells 44. Each hollow porous support member 42 has
at least one chamber 46 extending therethrough and comprises two
planar, parallel, flat surfaces 48 and 50 upon which the solid
oxide fuel cells 44 are arranged. Each solid oxide fuel cell module
40 is a sealed assembly, while allowing the flow of fuel through
the at least one chamber 46 in the hollow porous support member 42.
Each solid oxide fuel cell 44 comprises an anode electrode 52, a
cathode electrode 54 and an electrolyte 56. The solid oxide fuel
cells 44 are arranged such that the anode electrodes 52 are
arranged on the outer surface, the two planar, parallel, flat
surfaces 48 and 50, of the hollow porous support member 42, the
electrolytes 56 are arranged on the anode electrodes 52 and the
cathode electrodes 54 are arranged on the electrolytes 60. The
solid oxide fuel cells 44 are also arranged such that the anode
electrode 52 of one solid oxide fuel cell 44 is electrically
connected in series with the cathode electrode of an adjacent solid
oxide fuel cell 44. In this arrangement each solid oxide fuel cell
module 40 is arranged within a single inner vessel 58, and the
inner vessel 58 is arranged within an outer pressure vessel 60. In
this arrangement the inner vessel 58 defines a space 62 and a space
64 is defined between the inner vessel 58 and the outer pressure
vessel 60. There are means 66 to supply oxidant to the cathode
electrodes 54 of the solid oxide fuel cells 44 of the at least one
fuel cell module 40 and there are means 68 to supply fuel to the
anode electrodes of the solid oxide fuel cells 44 of the at least
one solid oxide fuel cell module 40. As the operating temperature
of the solid oxide fuel cells easily reaches the range of about
700.degree. C. to 1,000.degree. C., extra care must be taken to
ensure that the supplied fuel and oxidant do not mix, which would
otherwise lead to an explosion at such high operating temperature.
Mixing of the fuel and oxidant may result, for example, from a
rupture of the at least one chamber 46 or a leak in the anode
electrode 52, cathode electrode 54 or electrolyte 56. By placing at
least one wire 12 in the enclosed volume 10 in the inner vessel 58
as taught in the present invention, confirmation could be obtained
that enclosed volume 10 in the inner vessel 58 is above the
threshold temperature within a high degree of accuracy.
[0036] The present invention enables the selection of a physical
and electrical configuration of at least one wire 12 to reliably
infer that an enclosed volume 10 is either above the auto-ignition
temperature or that no more than a certain fraction is at or below
the auto-ignition temperature of a fuel/oxidant mixture. By
choosing the path of the at least one wire 12 so that it lies in a
thin region on the inside of a surface that encloses the volume 10
to be monitored and choosing the transition temperature of the at
least one wire 12 with knowledge of the heat transfer regime in the
enclosed volume 10, confirmation could be obtained that the
enclosed volume 10 is above the threshold temperature within a high
degree of accuracy.
[0037] The at least one wire may have two identifiable properties
and both identifiable properties change from a first identifiable
state at a temperature below the auto-ignition temperature of the
fuel/oxidant mixture to a second identifiable state at a
temperature above the auto-ignition temperature of the fuel/oxidant
mixture. As mentioned previously the at least one wire changes from
an oxidised state at temperatures below the auto-ignition
temperature of the fuel/oxidant mixture to a reduced state of
temperatures about the auto-ignition temperature of the
fuel/oxidant mixture. In addition to the change of electrochemical
state of the at least one wire the at least one wire also changes
from being electrically resistant at temperatures below the
auto-ignition temperature of the fuel/oxidant mixture because it is
in an oxidised state to being electrically conducting at
temperatures above the auto-ignition temperature of the
fuel/oxidant mixture because it is a reduced state.
[0038] Advantages of the present invention include the elimination
of costly high temperature thermocouples which are unreliable due
to junction degradation. A single electrical subsystem could be
employed for a large volume to be monitored where previously
electrical subsystems were required for every thermocouple placed
in the volume. The state of an enclosed volume 10 above the
auto-ignition temperature may be monitored with much less
instrumentation than before. In place of thermocouples, simpler
electronics may be used, allowing higher levels of safety to be
achieved with less analysis and testing/evaluation.
[0039] The present invention is applicable to devices operating at
high temperatures involving explosive fluids, and in particular to
fuel cells such as solid oxide fuel cells and reformers such as
hydrocarbon reformers.
* * * * *